Automated whole-volume measurement of CT fat fraction of the pancreas: correlation with Dixon MR imaging

Abstract

Objectives: This study aimed to assess the feasibility of pancreatic steatosis quantification by automated whole-volume measurement of the fat fraction of the pancreas on CT in comparison to magnetic resonance imaging (MRI) using proton-density fat fraction (PDFF) techniques. Methods: Fifty-nine patients who underwent both CT and MRI were analyzed. Automated whole-volume measurement of pancreatic fat on unenhanced CT was performed by a histogram analysis with local thresholding. Three sets of CT fat volume fraction (FVF) (%) values with thresholds of −30HU, −20HU and −10HU were compared to MR-FVF (%) values measured on a PDFF map. Results: The median −30HU CT-FVF, −20HU CT-FVF, −10HU CT-FVF and MR-FVF values of the pancreas were 8.6% (IQR, 11.3), 10.5% (IQR, 13.2), 13.4% (IQR, 16.1) and 10.9% (IQR, 9.7), respectively. The −30HU CT-FVF (%), −20HU CT-FVF (%) and −10HU CT-FVF (%) of the pancreas showed a significant positive correlation with the MR-FVF (%) of the pancreas (ρ = 0.898, p < 0.001, ρ = 0.905, p < 0.001, ρ = 0.909, p < 0.001, respectively). The −20HU CT-FVF (%) displayed reasonable agreement with the MR-FVF (%) with a low absolute fixed bias (mean difference, 0.32%; limit of agreement from −10.1 to 10.7%). Conclusion: The automated whole-volume measurement of the CT fat fraction of the pancreas using the threshold CT attenuation value of −20HU may be a feasible, noninvasive, and convenient technique for quantifying pancreatic steatosis. Advances in knowledge: CT-FVF value of the pancreas had a positive correlation with the MR-FVF value. The −20HU CT-FVF may be a convenient technique for quantifying pancreatic steatosis.

Diverse associations between pancreatic intra-, inter-lobular fat and the development of type 2 diabetes in overweight or obese patients

“…Due to ectopic fat, it is difficult to get satisfactory images using ultrasonography ( 29 ). Although CT is much more sensitive than ultrasonography, ionizing radiation limits its widespread use for pancreatic fat quantification ( 41 ). Recently, mDixon MRI has become widely used for quantifying pancreatic fat because of its reliable reproducibility and safety.…”

“…Recently, mDixon MRI has become widely used for quantifying pancreatic fat because of its reliable reproducibility and safety. Dixon images are highly correlated with CT images in pancreatic fat quantification ( 41 , 42 ). In this cross-sectional study, mDixon MRI was used to measure different parts of pancreatic fat in overweight and obese patients, saving them from the ionizing radiation of CT scanning, but with similar sensitivity.…”